Generally, in image forming apparatuses such as copying machines, printers, etc., using electrophotographic technologies, a latent image is basically formed on a photoreceptor having photoconductivity, the latent image is developed by electrostatically adhering insulation toner in which frictional electrostatic charge is obtained by rubbing with a carrier or an electrification member which constitutes part of a development apparatus, and then the formed toner image is transferred onto a transfer medium such as ordinary paper, film, etc., and subsequently, a copy image or a printed image is formed by fixing the toner image using heat, pressure, solvent vapor, etc., can be used.
In such an image forming apparatuses, as a method for fixing toners, a heat-rolling fixing method is generally used, since thermal efficiency is high, and high-speed fixing can be carried out, and the like, can be employed. In this method, the toner is fixed by contacting a transfer paper with a heating-roller in a fixing machine having a heating-roller. However, the method has a problem, called “offset” in which a subsequent image is contaminated by some of the toner adhering to the surface of the heating-roller during fixing and by re-transferring onto the paper. Furthermore, the method also has a problem, called “winding” in which paper jamming is caused by the winding of the transfer paper on the surface of the heating-roller. Such phenomena are easily caused in the case in which the viscoelasticity of the toner which melted by the heating-roller is not suitable and the viscosity and elasticity of the toner are not balanced. The viscoelasticity of the toner depends on the type of binding resin which is the main component of the toner, and the type and content of other components.
As a binding resin which is the main component of the toner, styrene-acrylic resin and polyester resin are generally used; however, recently, alicyclic olefinic resin (cycloolefinic resin) is being considered. The alicyclic olefinic resin is anticipated as a binding resin which will replace styrene-acrylic resin and polyester resin because this resin has various superior characteristics such as colorlessness and transparency, low-temperature fixity and high-speed fixity obtained by superior heat characteristics, sharp molecular weight distribution, superior grindability (high productivity and sharp particle size distribution), low hygroscopicity, being nonpolluting, etc. However, the alicyclic olefinic resin has problems in that offset phenomenon and winding phenomenon are easily caused in fixing of the toner, and fixing characteristics in a high temperature range is not sufficient since the molecular weight distribution is generally narrow.
As a method for preventing the occurrence of the offset phenomenon or the winding phenomenon and for improving fixability in a high temperature range, a method in which mold lubricants such as waxes having low molecular weight are introduced in the toner has been used generally. However, in this method, the toner particles are melted and adhered to each other, or the melted toner is easily adhered to charging members of the developing device, and consequently, melt contamination resistance is easily deteriorated and a uniform image is prevented from forming. Furthermore, in this method, since in producing the toner it is not easy for the mold lubricant to be uniformly and finely dispersed in the binding resin, melt contamination resistance is easily deteriorated when dispersibility is low. In addition, the formability of the toner is not sufficient since molding conditions for improving the dispersibility, etc., is not easily selected. The greater the introduced amount of the mold lubricant, the more readily the above problems occur. Therefore, it is difficult to improve fixabilities such as regarding offset, winding, etc., without deteriorating properties such as melt contamination resistance, etc., merely by introducing the mold lubricant. Here, the formability is the ease of production of the toner particle in which dispersion of raw material is superior and crushing is easy.
Patent Publication 1 is Japanese Unexamined Patent Application Publication No. 2003-114546. Patent Publication 2 is Japanese Unexamined Patent Application Publication No. 2001-272816. Patent Publication 3 is Japanese Unexamined Patent Application Publication No. Hei 10-73959.
Japanese Unexamined Patent Application Publication No. 2003-114546 discloses a full color toner for oilless fixing in which at least cycloolefin copolymer resin is contained as a binding resin, wax added as mold lubricant is contained at a total amount of 7 to 20 weight % to toner particle weight, and glossiness of the print image plane is 15 or more. The cycloolefin copolymer resin is a copolymer of α-olefin (acyclic olefin in a broad sense) such as ethylene, propylene, butylene, etc., and alicyclic compound having a double bond (cycloolefin) such as cyclohexene, norbornene, tetracyclododecene, etc., and the cycloolefin copolymer can be obtained by a conventional polymerizing method in which a metallocene-based or a Ziegler-based catalyst is used. However, in this Patent Publication, since a low molecular weight component (wax) is contained at 7 to 20 weight % to toner particle weight, the toner particles are melted and adhered each other, or the melted toner is easily adhered to charging members of a developing device, and consequently, melt contamination resistance is easily deteriorated. Furthermore, in this method, since in producing the toner, it is not easy for a large volume of the low molecular weight component to be uniformly and finely dispersed in the binding resin, formability of the toner is not sufficient, and melt contamination resistance is easily deteriorated when dispersibility is low.